Piston ring



Dec. 24, 1957 w, MARIEN 2,817,564

PISTON RING Filed Dec. 4, 1955 Mall 121 WT Mari e12 E7 i i-7575" UnitedStates Patent PISTON RING Melvin'W. Marion, Brentwood, Mo., assignor toRamsey Corporation, a corporation of Ohio Application December 4, 1953,Serial No. 396,168

15 Claims; (Cl. 309 -29) This invention relates to packing ringassemblies having cylinder wall-engaging rings held in operativepositions' by a combination expander and spacer ring.

Specifically, this invention deals. with an oil control piston ringassembly having top and bottom flat thin ring segments or rails and aself-expanding open-type wire ring between and behind the thin rings orrails to space and expand the thin rings or rails.

This invention will hereinafter be specifically described as embodied ina piston ring assembly for pistons of internal combustion engines but itshould be understood that the ring assembly of this invention isgenerally useful as a packing ring to control lubrication of relativelymovable parts.

This application is a division of my co-pending United States Patentapplication, Serial No. 303,465, filed August 9, 1952, entitled PistonRings, now U. S Patent No. 2,744,803, issued May 8, 1956.

According to this invention, there is provided a stack 0 rings includingtop and bottom flat thin steel ring segments and an intermediatecombination expander and spacer ring composed of wire. This intermediatering extendsfbetween and behind the steel rings or rails and is radiallycompressible and self-expanding to exert equal expansion loads aroundthe entire circumference of each of the thin rings or rails. These ringsor rails are preferably provided with chromium-plated rounded outerperipheries to presenthard wear-resisting edges to the cylinder wall.The expander and spacer ring is composed of spring-tempered wire bent tohave open spaces communieating with the oil vent holes in the piston forcontrolling drainage of oil between the two thin rings or rails.

An important feature of this invention resides in the provision of asingle wire ring having a dual capacity of supporting ring segments orrail-s in spaced operative position while, at the same time, radiallyexpanding these rings against the cylinder wall It is then an object ofthis invention to provide a packing ring having a plurality of thin flatsealing rings and a single circumferential expander and spacer ringcomposed of wire and holding the thin rings in spaced relation whileurging them outwardly around their entire periphery.

A further object of this invention is to provide a piston ring assemblyespecially adapted for the oil ring groove of pistons wherein a singlespring wire ring acts as both an expander and a spacer.

A further and specific object of this invention is to provide anexpansible piston ring composed of spring wire of circular cross-sectionbent to provide upstanding U- shaped segments alternately connected attheir top and bottom ends to form a spring which will develop its ownradial expansion force without being bottomed on the ring groove.

Qther and further objects of this invention will be apparent to thoseskilled in the art from the following detaileddescript-ion of theannexed sheet of drawings which,

by way of a preferredexample, illustrates one embodiment ofthis'invention.

On the drawings:

Figurel is a side. elevational view of aplston equipped with an oil ringassembly of this invention.

Figure 2 is an enlarged fragmentary vertical cross-sectional view takenalong the line lIll of Figure 1.

Figure 3. is a plan view of the wire expander. and spacer ring for theoil control piston ring assembly of this invention.

Figure 4 is an. exploded outside peripheral viewoi, the oil controlpistonring assembly.

Figure 5. is a.transversecross-sectional viewtaken along the line VV ofFigure 4.

Figure 6 is a fragmentary outside .peripheralview of the end portions ofthe expander and spacer ring showing; the manner in whichthese ends can.be. weldedltogether,

Figure. 7 is a fragmentary vertical crossssectional view showing thebottom oil. ring groove and oil control ring of Figure 2- on. a largerscaleand emphasizing the dishing of the rail ring.

As. shown on. the drawings:

In Figures 1 and 2,.thereterence numeral 10 designates generally apiston for andnternal combustion. engine. This piston is equippedwith.the conventional top. ring groove 1, middle ring groove 12, and oil ringgroove 13. Aconventional split solidcast iron. piston ring l4 is mountedin the top groove 11 to provide a compression seal. A. conventionalsplitcompression ring 15,,alsoof cast iron comr position, is seated inthe middle. groove. 12. These. rings 14 and 15 have broad. cylinderwall-engaging faces, 14a and 15a respectively.

The. oil ring groove 13 is wider than the: grooves 11. and 12. and is.joined through oil holes, such as 16, with the interior of the piston,This groove 13. has a top wall 13a and a bottom wall extending radiallyoutward from. a vertical back wall 13c which is, pierced at intervals bythe oil holes 16.

An oil control ring assembly 17 of this invention is mounted. in the oilgroove 13. This assembly 17 in,- cludes a top thin flat ring segment 18,an identical bottom ring segment 19, and an intermediate combinationex,- pander and spacer ring 20. The rings 13 and 19 have rounded outerperipheral edges 18a and 1911:, each covered with a layer of chromium orother hard corrosion. and wear-resisting metal 21 so that the cylinderwall-engaging edges of each ring are reinforced with a, hard coating.This coating can be applied by electro-plating, brazing, or in anysuitable manner. The inner peripheral edges of the rings 18 and 19 arealso rounded at 18]) and,19b respectively, but the inner peripheries arenot coated with the hard metal.

As shown in Figure 4, the thin ring segments or rails, 18 and 19 aresplit and gaps 22 and 23 are respectively pro vided between the ends ofthe rings. These gaps will vary in width even when the rings are in.operation on the piston 10 as shown in Figure 1, to permit radialcontraction and expansion of the thin rings.

The ring 20, on the other hand, has abutted-together ends 24 as shown inFigure 4. This ring 20, when radially compressed, will contract with aresilient spring-like action to exert an equal outward radial loadaround its entire periphery. Alternately, if desired, theabutted-together ends 24 of the ring 20, can be welded together as shownat 24a in Figure 6, thereby avoiding any possible installationdifiiculties arising from improper abutment of the ends. The continuousring 20, thus formed, can .be easily stretched over the head of thepiston 10 to snap into the groove 13. As a further alternative, suitablelock joints or connectors could also be used to secure together the ends24 of the ring 20.

The ring 20 is composed of wire of circular cross-section bent toprovide upstanding U-shaped segments alternately connected at their topand bottom ends to form a spring which will develop its own radialexpansion force without being bottomed on the ring groove. As shown inFigures 3 to 5, the ring 20 has radially spaced top and bottom parallellegs 20a with axial or vertically extending bight portions or legs 20bjoining the legs 20a at their outer periphery. Each leg 20a is outturnedat its inner edge to provide shoulders 20c and the offset wire portionsthen form connecting legs 20d joining the inner ends of the legs 20a. Asshown in Figure 2, the bight portion-s 20b extend between the rings 18and 19, the top and bottom legs 20a underlie these rings to supportthem, and the shoulders 20c abut the inner peripheries of the rings tourge them radially outward. The wire spring thus developed, separatesthe thin ring segments 18 and 19 and holds them against the top andbottom side walls of the ring groove while, at the same time, urging thering segments radially outward against the cylinder wall in which thepiston 11 operates. As shown, the shoulders 200 are inclined axiallyoutwardly and radially inwardly to act on the inner peripheries 18b andto 1% of the rail rings with an expanding force that has an axial vectoras well as a radial vector. This, of course, will bias the inner ends ofthe rings outwardly with more force than occurs along the flat legs soas to move the rails into conical shapes to tightly engage the sides ofthe ring groove at their inner e ges.

In the greatly enlarged view of Figure 7, the conical or dished shapesof the rails 18 and 19 are emphasized to illustrate how the inclinedshoulders 200 function in forcing the inner portions of the rails 18band 19b against the sides 13a and 13b respectively of the oil ringgroove 13.

From the above description it will, therefore, be understood that thisinvention provides a packing ring assembly wherein sealing rings areurged radially outward and are held in separated relation by aself-expanding spring wire ring which does not depend upon engagementwith the ring groove to exert its expanding force on the sealing rings.The self-expanding wire ring thus serves a dual function of an expanderand a separator in a packing ring assembly. The combination expander andseparator wire ring is open around its periphery so as not to impedefree drainage of oil in oil ring assemblies. The ring can be madecontinuous by welding or otherwise securing the ends together and theresulting complete annulus can be stretched over the head of the pistonand snapped into the oil ring groove.

It will be understood that modifications and variations may be effectedwithout departing from the scope of the novel concepts of the presentinvention.

I claim as my invention:

1. A combined expansion and spacer ring for packing assemblies whichcomprises a ring of wire having a circular cross-section, said wirebeing bent to provide a series of circumferentially spaced U-shapedsegments extending in a radial direction, top and bottom legs connectingthe U-shaped segments, and abutments provided by said legs adjacent theinner periphery of the ring to engage their ring segments on the innerperipheries thereof.

2. A piston ring comprising spring wire of circular cross-section bentto form radially spaced top and bottom legs joined by axially extendinglegs to constitute an open corrugated ring arrangement capable ofdeveloping its own radial force without being bottomed on a ring groove.

3. A packing ring assembly comprising top and bottom thin flat rail ringsegments having hardened cylinder wallengaging outer peripheries andopposed flat faces, a spring wire ring of circular cross-section betweensaid ring segments and having U-shaped segments extending in a radialdirection engaging the opposed fiat faces of the ring segments togetherwith top and bottom legs connecting the kU-Shaped segments .to hold themin spaced apart relation A ship, and abutments provided by said legsforming shoulders engaging the inner peripheries of said segments.

4. A packing ring assembly especially adapted for oil ring grooves andpistons which comprises top and bottom flat thin ring segments adaptedto lie against the top and bottom Walls of a ring groove, a combinationexpander and separator ring lying between and partially behind said thinflat rings, said combination ring being formed of spring wire ofcircular cross-section and having thin ringsupporting portions withoffset inner ends forming shoulders to engage the inner peripheries ofthe ring segments.

5. A piston ring comprising a spring wire annulus bent to support ringsin axially spaced relation in a ring groove and to urge said ringsoutwardly from the groove without being bottomed in the groove.

6. A spacer and expander piston ring which comprises a spring wireannulus adapted to be compressibly loaded to develop a radial expandingforce and having top and bottom legs for carrying piston ring railsegments.

7. A piston ring comprising a spring wire annulus composed of springwire of small cross-section bent to provide rail ring supporting legs.

8. A piston ring assembly comprising a pair of cylin der-engaging rails,and spacer and expander means including portions hearing at an angle tothe rails against the inner peripheries of the rails to cause the railsto dish and to spread the rails apart against the sides of the grooveand to force them radially outward, and other portions extending betweenthe rails for holding the rails in axially spaced relation.

9. A piston ring assembly comprising a pair of cylinder engaging rails,each having a rounded inner peripheral edge, and spacer and expandermeans for holding the rails in axially spaced relation and bearingagainst the rounded inner edges of the rails at an angle to each rail toforce them radially outward and to cause the rails to dish against thesides of the groove, the round edges of the rails facilitating slidingmovement of the rails on said means and sliding movement of the rails onthe sides of the groove in expanding.

10. A piston ring assembly comprising a pair of cylinder-engaging rails,each having a tendency to dish, and spacer and expander means forholding the rails in axially spaced relation, said means bearing againstthe inner peripheries of the rails atan angle thereto to cause the railsto dish toward the sides of the groove at their inner peripheries and toforce the rails radilly outward.

11. A piston ring assembly comprising a pair of cylinder-engaging rails,and a combined spacer and expander comprising a circumferentiallyexpansible structure U-shape in radial cross section with the arms ofthe U extending inwardly and holding the rails in axially spacedrelation, said arms being shaped to force the rails radially outward andto cause the rails to dish to force the inner portions of the railsagainst the sides of the groove.

12. A piston ring assembly comprising a pair of cylinder-engaging rails,and a combined spacer and expander comprising a circumferentiallyexpansible structure U-shape in radial cross section with the arms ofthe U extending inwardly and holding the rails in axially spacedrelation, the inner ends of said arms having outwardly flaring portionsbearing against the inner peripheries of the rails to force themradially outward and to cause the rails to dish against the sides of thegroove.

13. A piston ring assembly comprising a pair of cylinder-engaging rails,and a combined spacer and expander comprising a circumferentiallyexpansible structure U-shape in radial cross section with the arms ofthe U extending inwardly and holding the rails in axially spacedrelation, said circumferentially expansible structure comprising aplurality of circumferentially spaced web members connected by segmentsat the inner ends of the arms of the U, said segments having outwardlyflaring portions bearing against the inner peripheries of the rails toforce them radially outward and to cause the rails to dish against thesides of the groove.

14. A piston ring assembly comprising a cylinder-engaging rail, andpositioning and expander means for holding said rail at one side of thegroove, said means having portions bearing against the inner peripheryof said rail at an angle thereto to force the rail radially outward andto dish the rail toward said side of the groove at the inner peripheryof the rail.

15. A piston ring assembly comprising a pair of cylinder-engaging rails,and spacer and expander means for holding the rails in axially spacedrelation, said means bearing against the inner peripheries of the railsat an angle which is inclined axially outward and radially inward toexert an expanding force having axially outward as well as radiallyoutward force vectors.

References Cited in the file of this patent UNITED STATES PATENTS

